:root {
  --primary:      #0d1b2e;
  --accent:       #2563eb;
  --accent-muted: #3b82f6;
  --accent-bg:    #eff6ff;
  --text:         #1e293b;
  --muted:        #64748b;
  --border:       #e2e8f0;
  --surface:      #f8fafc;
  --white:        #ffffff;
  --radius:       10px;
  --shadow-sm:    0 1px 4px rgba(0,0,0,0.06);
  --shadow:       0 4px 20px rgba(0,0,0,0.07);
}

/* ── Reset & base ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body { font-family: 'Inter', sans-serif; color: var(--text); background: var(--white); line-height: 1.6; }
a { color: inherit; text-decoration: none; }

/* ── Layout ── */
.container { max-width: 1080px; margin: 0 auto; padding: 0 28px; }
section { padding: 72px 0; }
section.bg-alt { background: var(--surface); }

/* ── Nav ── */
.topnav {
  position: sticky; top: 0; z-index: 100;
  background: rgba(13,27,46,0.97);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(255,255,255,0.07);
}
.topnav-inner {
  display: flex; align-items: center; justify-content: space-between;
  max-width: 1080px; margin: 0 auto;
  padding: 0 28px; height: 50px; gap: 24px;
  overflow-x: auto; scrollbar-width: none;
}
.topnav-inner::-webkit-scrollbar { display: none; }
.topnav-brand { font-size: 14px; font-weight: 700; color: #fff; white-space: nowrap; flex-shrink: 0; }
.topnav-links { display: flex; gap: 2px; list-style: none; white-space: nowrap; }
.topnav-links a {
  color: rgba(255,255,255,0.55); font-size: 13px; font-weight: 500;
  padding: 5px 11px; border-radius: 6px; transition: color 0.15s, background 0.15s;
}
.topnav-links a:hover { color: #fff; background: rgba(255,255,255,0.08); }

/* ── Hero ── */
.hero {
  background: linear-gradient(150deg, #0d1b2e 0%, #1a3154 60%, #0d1b2e 100%);
  color: var(--white);
  padding: 76px 28px 64px;
  text-align: center;
  position: relative; overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute; inset: 0;
  background-image: radial-gradient(rgba(255,255,255,0.05) 1px, transparent 1px);
  background-size: 30px 30px;
  pointer-events: none;
}
.hero > .container { position: relative; }

.hero h1 {
  font-size: clamp(1.7rem, 3.5vw, 2.6rem);
  font-weight: 700;
  line-height: 1.2;
  max-width: 820px;
  margin: 0 auto 24px;
  letter-spacing: -0.02em;
}
.hero h1 em { font-style: normal; color: #60a5fa; }

.authors {
  font-size: 14.5px;
  color: rgba(255,255,255,0.78);
  margin-bottom: 6px;
  line-height: 1.9;
}
.authors a { color: #93c5fd; }
.authors a:hover { text-decoration: underline; }
.authors sup { font-size: 10px; color: #60a5fa; }

.affiliations {
  font-size: 13px;
  color: rgba(255,255,255,0.45);
  margin-bottom: 36px;
  line-height: 1.9;
}
.affiliations sup { font-size: 10px; color: #60a5fa; }

.btn-group { display: flex; gap: 10px; justify-content: center; flex-wrap: wrap; }
.btn {
  display: inline-flex; align-items: center; gap: 7px;
  padding: 9px 20px; border-radius: 7px;
  font-size: 13.5px; font-weight: 600; line-height: 1;
  text-decoration: none; border: none; cursor: pointer;
  transition: opacity 0.15s, transform 0.15s;
}
.btn:hover { opacity: 0.88; transform: translateY(-1px); }
.btn-primary { background: var(--accent); color: #fff; }
.btn-outline { background: rgba(255,255,255,0.08); color: #fff; border: 1px solid rgba(255,255,255,0.22); }

/* ── Stats bar ── */
.stats-bar {
  display: flex; justify-content: center;
  background: var(--white);
  border-bottom: 1px solid var(--border);
}
.stat {
  flex: 1; min-width: 120px;
  padding: 28px 20px; text-align: center;
  position: relative;
}
.stat + .stat::before {
  content: ''; position: absolute; left: 0; top: 22%; bottom: 22%;
  width: 1px; background: var(--border);
}
.stat .number {
  font-size: 2rem; font-weight: 800;
  color: var(--accent); line-height: 1;
  letter-spacing: -0.03em;
}
.stat .label {
  font-size: 11px; color: var(--muted);
  text-transform: uppercase; letter-spacing: 0.07em;
  margin-top: 5px; font-weight: 500;
}

/* ── Section headings ── */
.section-title {
  font-size: 1.6rem; font-weight: 800;
  color: var(--primary); text-align: center;
  letter-spacing: -0.02em; margin-bottom: 6px;
}
.section-title::after {
  content: ''; display: block;
  width: 36px; height: 3px;
  background: var(--accent); border-radius: 2px;
  margin: 10px auto 0;
}
.section-subtitle {
  text-align: center; color: var(--muted);
  max-width: 620px; margin: 14px auto 44px;
  font-size: 15px; line-height: 1.7;
}

/* ── Abstract ── */
.abstract-box {
  max-width: 800px; margin: 0 auto;
  font-size: 15.5px; line-height: 1.85;
  color: var(--text);
  border-left: 3px solid var(--accent);
  padding: 28px 32px;
  background: var(--white);
  border-radius: 0 var(--radius) var(--radius) 0;
  box-shadow: var(--shadow);
}

/* ── Method cards ── */
.method-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px; margin-top: 36px;
}
.method-card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px 22px;
}
.method-card .step-label {
  font-size: 11px; font-weight: 700;
  letter-spacing: 0.1em; text-transform: uppercase;
  color: var(--accent); margin-bottom: 10px;
}
.method-card h3 {
  font-size: 15px; font-weight: 700;
  color: var(--primary); margin-bottom: 8px; line-height: 1.3;
}
.method-card p { font-size: 13.5px; color: var(--muted); line-height: 1.7; }

/* ── Key insights box ── */
.insights-box {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px 28px;
  max-width: 800px; margin: 32px auto 0;
}
.insights-box h3 {
  font-size: 13px; font-weight: 700;
  color: var(--primary); margin-bottom: 14px;
  text-transform: uppercase; letter-spacing: 0.06em;
  display: flex; align-items: center; gap: 8px;
}
.insights-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(190px,1fr));
  gap: 12px;
}
.insight-item {
  display: flex; gap: 9px; align-items: flex-start;
  font-size: 13px; color: var(--muted);
}
.insight-item i { color: var(--accent); margin-top: 2px; flex-shrink: 0; font-size: 13px; }
.insight-item strong { color: var(--text); }

/* ── Figures ── */
.figure-wrap {
  margin: 32px auto;
  max-width: 940px;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  background: var(--white);
}
.figure-wrap img { width: 100%; display: block; }
.figure-caption {
  font-size: 13px; color: var(--muted);
  text-align: center; margin-top: 10px;
  font-style: italic; line-height: 1.6;
  padding: 0 8px;
  max-width: 860px; margin-left: auto; margin-right: auto;
}

/* ── Benchmark cards ── */
.benchmark-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px; margin-top: 36px;
}
.benchmark-card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px 22px;
  display: flex; flex-direction: column;
}
.benchmark-card .tag {
  display: inline-block; width: fit-content;
  background: var(--accent-bg); color: var(--accent);
  font-size: 10.5px; font-weight: 700;
  letter-spacing: 0.08em; text-transform: uppercase;
  padding: 3px 10px; border-radius: 999px;
  margin-bottom: 12px;
}
.benchmark-card h3 { font-size: 15.5px; font-weight: 700; color: var(--primary); margin-bottom: 8px; }
.benchmark-card p { font-size: 13.5px; color: var(--muted); line-height: 1.7; flex: 1; margin-bottom: 16px; }
.benchmark-meta {
  display: flex; gap: 12px; flex-wrap: wrap;
  padding-top: 14px; border-top: 1px solid var(--border);
  margin-top: auto;
}
.benchmark-meta .meta-item {
  display: flex; align-items: center; gap: 5px;
  font-size: 12px; color: var(--muted);
}
.benchmark-meta .meta-item strong { color: var(--text); }

/* ── Results tables ── */
.subsection-title {
  font-size: 15.5px; font-weight: 700;
  color: var(--primary);
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 6px;
}
.results-table-wrap {
  overflow-x: auto;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  margin-top: 12px;
}
table.results-table {
  width: 100%; border-collapse: collapse;
  font-size: 13px; background: var(--white);
}
.results-table thead tr { background: var(--primary); color: #fff; }
.results-table thead tr.subhead { background: #1a3154; }
.results-table th {
  padding: 11px 14px;
  text-align: left; font-weight: 600;
  font-size: 12px; letter-spacing: 0.03em;
  white-space: nowrap;
}
.results-table th[colspan] { text-align: center; border-bottom: 1px solid rgba(255,255,255,0.1); }
.results-table td {
  padding: 10px 14px;
  border-bottom: 1px solid var(--border);
  white-space: nowrap; color: var(--text);
}
.results-table tbody tr:last-child td { border-bottom: none; }
.results-table tbody tr:hover { background: #f1f5f9; }
.results-table tr.ours { background: var(--accent-bg); }
.results-table tr.ours:hover { background: #dbeafe; }
.results-table tr.ours td { color: var(--primary); font-weight: 600; }
.results-table .best { color: var(--accent); font-weight: 700; }

/* ── Analysis section ── */
.noise-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px; margin-top: 16px;
}
.noise-item .figure-wrap { margin: 0; max-width: 100%; }
.noise-item .figure-caption { margin-top: 6px; font-weight: 600; font-style: normal; }

/* ── Footer ── */
footer {
  background: var(--primary); color: rgba(255,255,255,0.38);
  text-align: center; padding: 32px 28px;
  font-size: 13px; line-height: 1.8;
}
footer a { color: rgba(255,255,255,0.55); }
footer a:hover { color: #fff; }

/* ── Scroll-to-top ── */
.scroll-top {
  position: fixed; bottom: 24px; right: 24px;
  width: 40px; height: 40px; border-radius: 50%;
  background: var(--accent); color: #fff;
  border: none; cursor: pointer; font-size: 17px;
  display: none; align-items: center; justify-content: center;
  box-shadow: 0 2px 12px rgba(37,99,235,0.35);
  transition: opacity 0.15s;
  z-index: 999;
}
.scroll-top:hover { opacity: 0.85; }
.scroll-top.visible { display: flex; }

/* ── Responsive ── */
@media (max-width: 860px) {
  .method-grid { grid-template-columns: 1fr; }
  .benchmark-grid { grid-template-columns: 1fr; }
  .noise-grid { grid-template-columns: 1fr; }
}
@media (max-width: 600px) {
  .stats-bar { flex-wrap: wrap; }
  .stat { min-width: 45%; }
  .stat + .stat::before { display: none; }
  .abstract-box { padding: 22px 20px; }
  .hero { padding: 56px 20px 48px; }
}